"The war against the Flood led to many technical advances. All proved fruitless. Improved Incineration Cannon that will unleash a long burst of energy blasts if allowed to charge up by holding the firing trigger."

The River of Light is a special variant of the Weapon/Anti-Materiel Z-390 High-Explosive Munitions Rifle, which appears in Halo 5: Guardians as an Ultra Rare REQ variant of the Incineration Cannon. As far as the chassis is concerned, the River of Light appears the same as a normal Incineration Cannon, except that it is colored black with orange stripes and paint wrapping around the weapon's main body and rear body, behind the trigger area.[4]

The River of Light was one of the first Incineration Cannons ever made. Its core was built and refined over decades by an unknown Promethean who effectively used the weapon and served in dozens of containment operations against the Flood.[6]

After the Domain was unraveled, the weapon was originally thought to be lost. However, it was later found in a Promethean cache in a factory that once spun impossible miracles of exotic matter. The forges of this factory were cold and abandoned for a hundred thousand years before the Warden Eternal returned with writs of control, dominance, and resurgence.[6]

While a Promethean Knight can't fully use the weapon's true potential, the artifact's heart knows its name and purpose, and hungers to be remembered once more by warriors whose hearts pump with life and limbs move with purpose and intent.[6]

The River of Light is classified as an Ultra Rare REQ, can be summoned in Warzone at Level 5 energy, and grants 150 REQ Points when sold. It is also available as the third of four special weapons in the campaign mission Reunion, found in a crevice in the area where the Warden Eternal is fought.

The River of Light comes with 25% upgraded battery capacity, a wider projectile arcing trajectory, no vertical recoil, and faster firing and charging speeds. Its charged shot is different in that it fires a long burst of seven arced explosive projectiles, thereby removing the disintegration aesthetic that other versions of the Incineration Cannon carry. However, compared to the normal Incineration Cannon and Heartseeker, the weapon's battery depletes twice as fast if it is kept charged. Overall, the River of Light is useful for dealing damage onto a large target, such as a vehicle or boss. Unlike the other Incineration Cannons, the River of Light cannot kill a campaign playable character and make them unrevivable.

In Warzone, Legendary Promethean Knight bosses mostly use the River of Light as their primary weapon, while Mythic Knights are usually armed with the advanced Heartseeker instead.